Electrical energy demands in the United States are steadily increasing, whereas energy resources are continually decreasing. This situation emphasizes the need for improved and higher efficiency energy conversion systems. However, the majority of power generating systems utilize the Rankine cycle, which cycle appears to have been improved to the point that increasing its efficiency has become very difficult.
We have discovered that the absorption/regeneration cycle system that has been used extensively in refrigeration and air conditioning systems is capable of improvement to exceed the efficiency of the Rankine cycle. To this end, we have developed a novel method of utilizing this cycle for generating electrical power, producing refrigeration, and utilizing the waste heat from the cycle to perform additional useful work, thereby achieving this objective in an admirable manner.
The thermodynamic cycle efficiency of the most modern fossil fuel turbine type power plants may be in the range of 35 to 45 percent and therefore involves a large amount of waste heat. To achieve high turbine efficiency, the turbine exit pressure must be kept low and inasmuch as exit temperature is dependent on exit pressure, the waste heat is necessarily rejected at a lower temperature. Not only is this low waste heat temperature difficult to use for any useful purpose, but it also requires large volumes of cooling water and generates undesirable thermal pollution. By contrast, in the absorption/generation cycle, the heat rejection temperature is not solely dependent on the turbine exit pressure and it is possible to run with low turbine exit pressure and relatively high heat rejection temperature. Thus, the higher temperature associated with the heat rejection greatly increases the opportunity for effectively utilizing the rejected heat.
Prior art absorption/regenerative power cycle systems have been primarily utilized solely for refrigeration purposes and have used a variety of carrier fluid-working fluid pairs. For example, the Hartman U.S. Pat. No. 3,124,939 teaches a method of refrigeration using this power cycle, with carbon dioxide and potassium carbonate solution as the fluid pair. The Randel U.S. Pat. No. 1,922,217 recites the use of a mixture of butane and carbon dioxide with potassium carbonate, the CO.sub.2 aiding in the flow of the butane. The Kasley U.S. Pat. No. 1,506,530 teaches a two-fluid closed cycle refrigeration process having a hermetically sealed system. A system for generating power from a refrigerant is described by Mamiya, U.S. Pat. No. 3,505,810. Latter patentee teaches the use of the refrigerant to drive a turbine after superheating. While the prior art has explored the absorption/regenerative power cycle, there has been no recognition of the novel capability of greatly increasing the overall efficiency of the cycle by a combination that increases the waste heat temperature to a range can perform useful work while simultaneously generating electrical power and producing refrigeration.